General magnetic reconnection, parallel electric fields, and helicity
Analyzing the qualitative three-dimensional magnetic structure of a plasmoid, we were led to reconsider the concept of magnetic reconnection from a general point of view. The properties of relatively simple magnetic field models provide a strong preference for one of two definitions of magnetic reconnection that exist in the literature. Any concept of magnetic reconnection defined in terms of magnetic topology seems naturally restricted to cases where the magnetic field vanishes somewhere in the nonideal (diffusion) region. The main part of this paper is concerned with magnetic reconnection in nonvanishing magnetic fields (finite-B reconnection), which has attracted less attention in the past. We show that E/sub parallel/ (the electric field component parallel to the magnetic field) plays a crucial physical role in finite-B reconnection, and we present two theorems involving E/sub parallel/. The first states a necessary and sufficient condition on E/sub parallel/ for global reconnection to occur. Here the term ''global'' means the generic case where the breakdown of magnetic connection occurs for plasma elements that stay outside the nonideal region. The second theorem relates the change of magnetic helicity to E/sub parallel/ for cases where the electric field vanishes at large distances. That these results provide new insight into three-dimensional reconnection processes is illustrated in terms of the plasmoid configuration, which was our starting point. copyright American Geophysical Union 1988
- Research Organization:
- Ruhr-Universitaet Bochum, Bochum, Federal Republic of Germany
- OSTI ID:
- 6907572
- Journal Information:
- J. Geophys. Res.; (United States), Vol. 93:A6
- Country of Publication:
- United States
- Language:
- English
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SUPERCONDUCTIVITY AND SUPERFLUIDITY
PLASMOIDS
MAGNETIC RECONNECTION
ELECTRIC FIELDS
HELICITY
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MATHEMATICAL MODELS
TOPOLOGY
EARTH ATMOSPHERE
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640410* - Fluid Physics- General Fluid Dynamics